Lout belongs to a large group of words that we use to indicate a particular sort of offensive and insensitive person, that group also including such terms as boor, oaf, jerk, and churl. We've used lout in this way since the mid-1500s. As early as the 800s, however, lout functioned as a verb with the meaning "to bow in respect." No one is quite sure how—or even if—the verb sense developed into a noun meaning "a brutish person." The noun could have been coined independently, but if its source was the verb, perhaps the awkward posture of one bowing down led over the centuries to the idea that the bowing person was base and awkward as well.